Bad Dialing

how did my son's laptop dial up an overseas porn site without him knowing it? He swears he did not command his computer to do this - that there was no popup that asked him to dial when he went to this gaming site that dialed up an international porn site - what could be going on with this? Verizon says it is my carrier's fault - Internt America -

Either
A-Her son is lying
B-He signed a digital Cert. saying that it was okay
C-She just has no clue what happened

She told me that she was right there when he went to the gaming site and watched him play games. Then next thing she knows she is being hit with a HUGE fee for overseas charges and she can't do anything about it.

Verizon is the only provider out here and there is nothing we can do about it. Any suggestions?